Water turrets or “monitors” are used to manually or automatically distribute high-pressure streams of foam, water or water-based foam over an area determined by the angle of elevation of the monitor, its arc of oscillation, its speed of oscillation and its pattern of oscillation. Monitors are primarily used to extinguish fire hazards, although other uses may include fire prevention, irrigation, crowd control, and water-cooling of objects.
Monitors are often configured as rotatable or oscillating types having a fixed input portion and a rotatable output portion. A water-driven turbine in the fixed portion is used to convert water flowing through the monitor to rotary mechanical motive power. The mechanical motive power is coupled to a rotary-to-oscillatory motion converter which is in turn coupled between the fixed and rotatable portions of the monitor, causing the rotatable portion to move in a predetermined or determinable pattern defined by the characteristics of the motion converter.
Oscillating monitors typically include a rotatable flange having ball bearings between the fixed portion and the rotatable portion to reduce rotational friction between these components and to support radial and axial loads exerted upon the rotatable portion. A pair of races are utilized to contain a plurality of balls and to transmit the loads through the balls, one race being formed in the fixed portion and a facially adjacent race being formed in the rotatable portion. As the race in the rotatable portion moves it causes the balls to rotate as well. Because the balls are rolling they have a lower coefficient of friction than if two flat surfaces were rotating upon each other.
A significant drawback of the ball bearing arrangement in a rotatable flange is that the balls are typically fabricated of much harder material than the portions of the flange containing the races. For example, the balls are typically made of steel while the races are made of brass. This results in rapid wear of the races and subsequent loss in the integrity of fit between the rotatable and fixed portions of the rotatable flange. Furthermore, because of physical limitations of the rotatable flange arrangement the ball bearings must be installed into the races after the rotatable and fixed portions are joined together. Consequently, a fill port must be provided to either or both the fixed and the rotatable portions of the monitor to facilitate installing the balls in the races, complicating the tooling used to fabricate the monitor. Furthermore, a closure such as a cap or cover must also be provided to close off the port once the balls are installed. In addition, the installation of the balls into the races is laborious and time-consuming. It is therefore desirable to reduce the labor associated with the ball bearing assembly and increase reliability.
An additional limitation of present monitors is that the sweep range of their pattern of oscillation is generally limited to about 120 degrees. This range is often insufficient, requiring that the monitor be moved or repositioned periodically in order to obtain the desired coverage.
A further limitation of present monitors is that the rotary-to-oscillatory conversion mechanism is not sufficiently robust. Consequentially, the mechanism is subject to deformation—often further limiting the sweep range of the monitor—or failure altogether, rendering the monitor unusable for its intended purpose.
There is a need for a monitor having an improved bearing system. There is further need for a monitor having a wider sweep range and a robust rotary-to-oscillatory conversion mechanism.